There seems to be a big misunderstanding about the use of the arch when executing the bench press. I’ve seen an overwhelming amount of guys giving unwanted and highly misinformed advice to female lifters in particular about arching their back in the bench press, claiming that this technique will “snap their backs” or “break their necks”, or even saying that this technique is “like cheating”. In this article I’ll talk about basic biomechanics, anatomy of the shoulder and the purpose of arching in the bench press, based on FACTS and EVIDENCE.
Ever wondered why you can move more weight doing a decline bench press? Because of the muscle fiber alignment of the pecs (angle of pennation), arching your UPPER back in a bench press, promotes better recruitment of the lower fibers of the pectoralis major, similar to the decline bench, which means that a larger portion of your chest muscle fibers will be activated to produce force.
Every heard of the term closed pack position? This refers to the position of most joint congruency and ligamentous stability. By arching your UPPER back and retracting your scapulae back together, you’re now placing your glenohumeral joint in a fully abducted and externally rotated position. This position of the humerus is a safer and more stable position to push from than if your upper back was flat against the bench.
The true question is WHY are you benching? If your goal is shoulder health and you are too worried about getting hurt, stay away from the bench press. If your goal is to maximize your athletic potential AND stay healthy, follow my previous advice.
If you are a powerlifter and your goal is to lift the most amount of weight, arching your LOWER back might give you some advantage by shortening the range of motion of the lift. In terms of safety of the lower lumbar segments, I would advice lifters to keep their whole buttocks in contact with the bench to avoid putting the back in end ranges of flexion, which could potentially be harmful. The rules of powerlifting indicate that the butt must remain in contact with the bench throughout the entire lift.
No study has shown this position to be harmful for the lumbar spine, EXCEPT when HYPEREXTENDING, which has been shown to increase shear forces in the limbo-sacral area specifically.
By: Stefanie Cohen, SPT